The present invention pertains to a high-precision radar range finder, whose design corresponds to the FMCW principle, the radar range finder operating in a frequency range of 24.125 GHz.+-.125 MHz, the range finder being particularly useful for closed containers.
Besides other fields of use, this device is preferably used in the level measuring technique. A great variety of designs of level meters have been known. The contactless level metering methods are based, besides radar methods, preferably on the travel time measurement in the ultrasound range or in the laser range. The ultrasound sensors have the drawback that the velocity of propagation of sound changes with the medium whose level is to be measured, as a result of which very substantial errors in measurement occur. The laser sensors have the drawback that, aside from the high purchase price, the level cannot usually be recognized in the case of clear liquids, because the laser beam is reflected from the bottom of the container rather than at the level. The radar sensors are free of these drawbacks.
The requirements imposed on a radar sensor are, aside from the high degree of reliability required, the measurement of the level to an accuracy in the cm range. Compliance with various regulations is required including specified frequency bands (FCC in the U.S.A. and FTZ-German Federal Central Bureau of Telecommunications) and others (e.g., approval by the German postal administration, as well as compliance with the protection requirements of the German Federal Institute for Physics and Technology, Group 3.5 "Explosion Protection of Electrical Equipment").